Forget the spell ever happened. Ground yourself, don't focus on it, until it actually works. To do that otherwise is to irrevocably mess up the spell by tangling yourself in attachments, pulling it down with doubts and fears, and creating thought forms that work against it.

Also i recommend not grouping magic into categories like "black" or "white", they cause you to feel like you deserve to be punished for using it and therefore you're more open to backlash.

Not that the chances are really high of any form of backlash from a money spell coming in the form of physical pain unless you over-exerted your energy body which is unlikely considering someone else did the spell for you.

Divine on it with a clear, un-biased mind. Check if it actually is a side effect of the spell.